1. Field of the Invention
The present invention relates to a resin-sealed type semiconductor device having an electronic component encapsulated in a molded resin package, and a heat spreader incorporated in the molded resin package to facilitate radiation of heat from the electronic component, and also relates to a production method for manufacturing such a resin-sealed type semiconductor device.
2. Description of the Related Art
In general, a resin-sealed type semiconductor device is produced by using a lead frame including a mount stage and a plurality of leads. In particular, first, an electronic component, such as a semiconductor chip, is mounted on the mount stage, and then the respective leads are electrically connected at their inner ends to terminal pads formed and arranged on the electronic component through bonding wires. Subsequently, the electronic component is placed together with the mount stage in a molding cavity defined by a metal mold, such that the leads extend outward through the metal mold. Thereafter, a suitable resin material is injected into the molding cavity, whereby the electronic component, the mount stage, and the inner lead sections of the leads are enclosed with and encapsulated in the molded resin package, with outer lead sections of the leads being protruded from the molded resin package, resulting in the production of the resin-sealed type semiconductor device.
When the electronic component generates a large amount of heat in operation, a heat spreader is incorporated and buried in the molded resin package, to thereby facilitate radiation of heat from the electronic component, as disclosed in, for example, Japanese Laid-Open Patent Publications (KOKAI) No. 2000-294712 and No. 2001-156235. In particular, the heat spreader is made as a suitable metal sheet, such as a copper sheet, a copper alloy sheet or the like, having a thickness of 100 to 250 μm, and is formed with a plurality of protrusions or ribs. The heat spreader is associated with the mount stage such that the protrusions or ribs are in contact with the rear face of the mount stage, so that the heat is transmitted from the electronic component to the heat spreader through the intermediary of the mount stage.
Of course, the incorporation of the heat spreader in the molded resin package results in an increase in an entire thickness of the molded resin package, and this is contrary to the trend in which the thickness of resin-sealed type semiconductor devices should be made as small as possible. Although the entire thickness of the molded resin package can be reduced by thinning a skin layer of the molded resin package, this skin layer must have a thickness of more than 200 μm, before it is possible to prevent penetration of moisture into the molded resin package. Otherwise, wiring patterns, included in the molded resin package, are subjected to premature corrosion. Note, usually, the wiring patterns are made of aluminum.
In any event, conventionally, there are no proposals for reducing the entire thickness of the molded resin package without thinning the skin layer of the molded resin package.